Government Services. From distributing tax forms to taking passport photos and delivering ballots overseas, the US mail moves government services. USPS is the only delivery service that reaches every mailbox in the nation, including PO Boxâ¢ addresses and APO/FPO/DPO addresses. Passport Services.
1 Dorsal fins are found on the back of the fish. 2  There may be up to three of them. 3  The fish uses this fin for balance in the water and sudden movements. 4  Caudal fins are also known as tail fins.5  This is what we refer to as the fish's tail. 6  Anal fins are on the ventral (bottom) surface of the fish, behind the anus. Dorsal fins are found on the back of the fish. 2  There may be up to three of them. 3  The fish uses this fin for balance in the water and sudden movements. 4  Caudal fins are also known as tail fins.
There is a reason that fish are so slimy, and it's very important for the survival of fish. Slime is secreted from cells in the very outside layer of the skin. In some cases, the placement of these slime-producing cells determines what species of fish it is. The cells produce what is called a glyco-protein, which is then mixed with the water making the slimy mucus. Slime is important for fish to regulate many necessary body functions, including protection against parasites. Some parasites can't attach to the scales because they are too slippery; others suffocate in the slime. Slime also acts as a band-aid, covering wounds and scrapes.